The present invention relates to apparatus for ascertaining the upper level of a supply of a flowable medium, e.g., a liquid, which is stored in a vessel, e.g., in an upright cylindrical tank. More particularly, the invention relates to improvements in apparatus of the type wherein files or rows of resistors and associated electric switches are mounted on an elongated insulating carrier which is adjacent to the path of upward or downward movement of a float. The float rides on the body of liquid in the vessel and carries a permanent magnet which actuates the nearest switch or switches to thereby change the number of resistors which are connected in circuit with an indicating instrument.
A somewhat similar apparatus is disclosed in U.S. Pat. No. 3,656,074 granted Apr. 11, 1972 to Bevilacqua et al. The patented apparatus employs an insulating carrier adapted to be flexed to the extent which is necessary to allow for its introduction into a slightly arcuate insulating pipe. The carrier cannot be folded or convoluted. Therefore, the manipulation of such apparatus presents serious problems when their components must be transported between different locales of use, especially if the length of the component parts must suffice to ascertain the upper level of liquid in a relatively large vessel, e.g., in a vessel wherein the upper level of liquid is located at several meters above the bottom wall. Similar problems arise when the apparatus must be removed from a vessel for the purpose of inspection and/or repair.
Attempts to assemble the insulating carrier for switches and resistors of several shorter sections which are coupled to each other at the locale of use, provided that the depth of the vessel warrants the use of two or more interconnected carrier sections, have met with negligible success because any shortening or lengthening of the carrier invariably entails a considerable amount of work which must be performed by skilled operators. Such work involves proper calibration of the indicating instrument whose pointer or another mobile part indicates or records the ascertained upper level of liquid in the vessel. Moreover, the resistance of connections between the conductors on discrete sections of the insulating carrier must be taken into consideration whenever the length of the carrier is increased or reduced.
An object of the invention is to provide a novel and improved apparatus for ascertaining the upper level of a supply of flowable material in a vessel or the like.
Another object of the invention is to provide an apparatus whose parts can be readily taken apart for transport from one locale of use to another locale of use or to storage.
A further object of the invention is to provide a novel and improved guide for the switch actuating means in an apparatus of the above outlined character.
An ancillary object of the invention is to provide novel and improved means for changing the length of the apparatus.
A further object of the invention is to provide a novel and improved support for the switch actuating means in an apparatus of the above outlined character.
An additional object of the invention is to provide novel and improved means for testing and calibrating the apparatus.
A further object of the invention is to provide the apparatus with novel and improved means for permitting insertion and/or withdrawal of component parts which generate signals denoting the level of flowable material in a vessel wherein the apparatus is installed.
One feature of the invention resides in the provision of an apparatus for ascertaining the upper level of a supply of liquid which is confined in a vessel. The apparatus comprises an elongated conduit which is permeable to liquids and is installed in the vessel in upright position so that the upper level of liquid in the conduit at least approximates but normally matches the upper level of the supply of liquid in the vessel, a float which is disposed in the conduit and includes a permanent magnet or other suitable switch actuating means, an upright pipe adjacent to the conduit, and a plurality of electrical components sealingly confined in and being withdrawable from the pipe. The components include a row of spaced-apart electric switches which can be actuated by the actuating means whereby the actuation of a switch which is adjacent to the float denotes the upper level of liquid in the conduit. The pipe and the conduit comprise a plurality of superimposed sections and means for coupling the neighboring sections to each other. If the actuating means is or includes a permanent magnet, the pipe and the conduit preferably consist of magnetically neutral material. Those portions of the pipe which form part of the sections are preferably of the same length as the corresponding portions of the conduit.
The coupling means may comprise flanges at each end of each section and bolts and nuts or other suitable fastener means for securing the abutting flanges of neighboring sections to each other.
The sections are decoupled from each other prior to withdrawal of the pipe and conduit from a vessel, e.g., in order to transport such parts to storage or to a different locale of use. The number of assembled sections depends on the depth of the vessel. The electrical components can be installed on an insulating band which is confined in a flexible hose of insulating material and which is withdrawn from the pipe prior to separation of abutting flanges from each other.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.